Aerosol dispenser for fluid products comprising a piston pump assembly for generating compressed air serving as propellant and a product metering device

ABSTRACT

An aerosol dispenser for fluid products which comprises a container, A PISTON PUMP ASSEMBLY MOUNTED THEREIN FOR GENERATING COMPRESSED AIR PROPELLANT, A SPRAY NOZZLE FIXEDLY MOUNTED IN THE PISTON, A COMPRESSED AIR FLOW PATH EXTENDING FROM THE PISTON PUMP TO THE SPRAY NOZZLE, A COMPRESSED AIR FLOW CONTROLLING VALVE IN THE FLOW PATH, A PRODUCT FLOW PATH EXTENDING THROUGH THE PISTON SEPARATE FROM THE AIR FLOW PATH WITH A PRODUCT FLOW CONTROL AND A PRODUCT METERING DEVICE MOUNTED THEREIN; AND A CONNECTION EXTENDING FROM THE VALVE THROUGH THE AIR FLOW PATH AND ENGAGING THE PRODUCT FLOW CONTROL, THEREBY OPENING THE PRODUCT FLOW PATH IN CONJUNCTION WITH THE FLOW OF COMPRESSED AIR.

United States Patent 1 Maier AEROSOL DISPENSER FOR FLUID PRODUCTSCOMPRISING A PISTON PUMP ASSEMBLY FOR GENERATING COMPRESSED AIR SERVINGAS PROPELLANT AND A PRODUCT METERING DEVICE [75] Inventor:

[73] Assignee: Ciba-Geigy Corporation, Ardsley,

[22] Filed: Dec. 20, 1973 [21] Appl. No.: 426,757

Christian Maier, Munich, Germany [30] Foreign Application Priority DataDec. 22, 1972 Switzerland 18730/72 [52] US. Cl. 222/193, 222/207 [51]Int. Cl B67d 5/54 [58] Field of Search 222/193, 207, 213, 385,

[56] References Cited UNITED STATES PATENTS 10/1953 Ingell 239/356 X4/1966 Corsette et a1. 222/385 X Jan. 14, 1975 Bons 239/333 X Donoghue222/207 Primary ExaminerStanley H. Tollberg Assistant ExaminerNorman L.Stack [57] ABSTRACT An aerosol dispenser for fluid products whichcomprises a container,

a piston pump assembly mounted therein for generating compressed airpropellant,

a spray nozzle fixedly mounted in the piston,

9 Claims, 5 Drawing Figures I llll% l [II /[Ill PAHIN I EU JAN 1 4 i975sum 1 or d iii n PATENTED JAN 1 19 5 sm-zu 20F PATENTEU JAN 1 4191s sawu or 4 AEROSOL DISPENSER FOR FLUID PRODUCTS COMPRISING A PISTON PUMPASSEMBLY FOR GENERATING COMPRESSED AIR SERVING AS PROPELLANT AND APRODUCT METERING DEVICE This invention relates to aerosol dispensers forfluid products, comprising a piston pump assembly for generating, in theinterior of the dispenser, compressed air serving as propellant, and aproduct metering device.

Various types of aerosol dispensers utilizing compressed air fordispensing fluids in the form of a spray are known. Among them areespecially aerosol dispensers for liquid products described in U.S. Pat.3,369,757 granted in Feb. 1968 to M. Boris, which dispensers comprise acontainer for product to be dispensed, a piston pump separately from theproduct container and having a piston and a cylinder, for generatingcompressed air as a propellant, a spray nozzle in which compressed airflowing therethrough aspirates, and from which it sprays in aerosolform, product from the product container, flowpaths for compressed airand product to the spray nozzle from, respectively, the piston pump andthe product container, and obturating means associated with the saidflowpaths and opening these paths in dependence on a determinedcompression position of the piston in the cylinder of the aforesaidpiston pump.

These known dispensers suffer from the drawback that the timely openingof the obturating means for the compressed-air flow which comprise aspring-biassed ball valve, is effected by the pressure of the compressedair alone, and hence not reliable as it depends on the quality and ageof the spring material, and the valve must open before a valve shaftcontrollingthe product flowpath. can open. This leads unavoidably to aloss of compression.

In order to overcome this drawback, there is described in Belgian PatentNo. 768,039, granted on Dec. 3, 1971 to the Applicant, an improved typeof theabove-described aerosol dispensers, wherein at least the valvecontrolling the flow of. compressed air is opened: by the mechanicalaction of rigid positive force-transmitting means comprising abutmentmeans on the piston of thepiston pump andona displaceable valve disk orstem or the. like valve body pertaining to the compressed-airflow-controlling valve, whichzabutment means on the piston andv valvebodyact one upon the other by direct contact or onlever means acting onthe aforesaid valve body.

In these known dispensers, the productcontainer means is directlyconnected to the spray nozzle and is normally above the spray nozzleduring actuation of the dispenser. Thus, the whole body ofproduct'issubjected to aspiration during each operation of thedispenser. To keep the dispenser a convenient size, the productcontainer is made relatively small.

This is also the case in another type of the applicant's aerosoldispensers for fluid products which comprises a container for product tobe dispensed, a piston'pump separately from the product container, forgenerating compressed air as a propellant, a spray nozzle in whichcompressed air flowing therethrough aspirates, and sprays, product fromthe product'container, flowpaths, for compressed air from the pistonpump, and for product from the product container, to the spray nozzle,valve means comprising valve housings and displaceable valve bodies inthe housings and being associated with the said flowpaths and openingthe paths dependent on the piston approaching or reaching fullcompression stroke position in the cylinder of the aforesaid pistonpump, abutment means in the piston pump acting, in the aforesaidcompression stroke position, by direct mechanical contact on at leastthe valve body of the compressed air flow-controlling valve means; and amounting for the said spray nozzle; and wherein the said productcontainer and product flow control means are mounted on the saidmounting and the said mounting is detachably connected to the piston ofthe said piston pump, forming a mounting-piston assembly; and whereinthe said piston is hollow and constitutes the housing for the remainingparts of the said compressed air-controlling valve means being mountedin the piston.

The applicants have also found that, with this lastmentioned and similardispensers developed by them, it may in some cases be difficult to timethe outflow of product from the product container to the spray nozzle sothat such outflow ceases exactly with, or shortly before, the ending ofthe flow of compressed air through the spray nozzle, when the opening ofthe product flowcontrolling means is effected by direct, positiveengagement of the latter with the aid of engaging means provided on thecompressed air flow-controlling valve member.

It is, therefore, a first object of the instant invention to provide anaerosol dispenser of the last-mentioned type, in which the amount ofproduct available for each dispensing operation is so limited that itwill cease before the flow of compressed air from the piston pumpthrough the spray nozzle ceases entirely, when the said control valve isopened by direct mechanical contact as described above.

It is another object of the present invention to provide an improvedfluid product aerosol dispenser of the type described above which has alarger, product container means in a part of the dispenser where it doesnot unduly increase the bulk of the latter or make it awkward to handle,and a product metering device between the product container means; andthe productaspirating spray nozzle.

Yet another object of the invention is to provide a fluid productaerosol dispenser of the type described in which the metering device andthe product container means are arranged so that byinverting thedispenser and then righting it, only a small-amount of product isplaced-in position to be dispensed.

These objects are achieved by the provision of an aerosol dispenser forfluid products, comprising container means for product to be dispensed;

, a piston pump separately from the product container and having apiston and a cylinder;

a spray nozzle in which compressed air flowing therethrough aspirates,and from which it sprays, product in aerosol form;

duct means for compressed air flow, extending from said piston pump tosaid spray nozzle;

compressed air flow-controlling valve means in said flowpath andcomprising a valvemember movable in valve housing and obturatingthecompressed air flowpath'when closed;

a product flowpath separate from said compressed air flowpath, andproduct flow control means in said prod uct flowpath,

and engaging means provided on at least one of the said valve member andthe said cylinder for direct mechanical engagement of the said valvemember and cylinder with one another, as the piston approaches orreaches the end position of its compression stroke in the cylinder, formoving at least the said valve member to open the compressed airflowpath; the said engaging means also comprising means for directmechanical engagement of the product flow control means for opening thelatter at the same time as, or a brief instant prior to, the opening ofthe compressed air flowpath; at least the front end part of said pistonextending into said cylinder constitutes the said valve housing of thecompressed air flow-controlling valve means, the said spray nozzle beingfixedly mounted in said piston, the said duct for compressed air flowextending through the piston, a product metering device being mounted onthe said piston adjacent said spray nozzle in said product flowpath, andsaid product flow control means being located between said meteringdevice and said spray nozzle, the said product container meanscomprising a product reservoir surrounding the cylinder of said pistonpump and the said product flow-path extending from said reservoir tosaid metering device through a part of said piston, sealingly separatedfrom the air compression space in said cylinder.

In preferred embodiments of the aerosol dispenser according to theinvention, one or several of the following advantageous features can bepresent:

1. Spring means in the cylinder can engage the front end of the pistonfacing into the cylinder and urging the piston out of the cylinder.

2. One-way valve means for admitting air into the cylinder during thereturn stroke of the piston can be mounted in the wall of the cylinder.

3. The engaging means can comprise an abutting part on the inside of thebottom end wall of the cylinder of the piston pump, and a projection ofthe valve member extending out of the front face of said piston facingtoward the cylinder bottom end wall when out of contact with theabutting part.

4. The compressed air flow-controlling valve means can comprise springmeans and avalve seat in the valve housing, which spring means urge thevalve member against the valve seat.

5. A valve body of the product flow control means can be biassed towardclosed position and comprise abutting means in an open end of thecompressed air flow duct of the piston and the valve body of thecompressed air flow-controlling valve means can bear contact rod meansextending through the said duct and engage the abutting means of theproduct flow control means and thereby open the product flowpath, whenthe abutment means in the piston pump act on the valve member of thecompressed air flow-controlling valve means.

6. The product flow control means can comprise valve seat means engagedby the product valve body when in closed position and elasticallydeformable membrane means engaging the product valve body and biassingthe latter into engagement with the valve seat means.

Structural and operational features of a similar aerosol dispenser andof a preferred embodiment of the dispenser according to the inventionare shown in detail in the accompanying drawings and will be readlyunderstood therefrom taken alone or together with the descriptionthereof following hereinafter. In these drawings:

FIG. 1 is an axial sectional view of a similar aerosol dispenser(lacking means for actuating mechanically the product flow controlmeans) with the parts in the non-dispensing positions;

FIG. 2 is an axial sectional view of the upper part of the dispensershown in FIG. 1 with the parts in the dispensing positions;

FIG. 3 is an enlarged cross-sectional view of the embodiment shown inFIG. 1 taken along the line III III therein;

FIG. 4 is an axial sectional view of the upper part of a preferredembodiment of an aerosol dispenser according to the invention with theparts in nondispensing positions, and having improved product flowcontrol means; and

FIG. 5 is an axial sectional view of the embodiment shown in FIG. 4, butwith the parts in dispensing positions.

In these figures, like parts are designated by like numerals. Theearlier dispenser shown in FIGS. 1 to 3 comprises a piston pumpconsisting of the cylinder 1, the piston 2, a return spring 3 urging thepiston 2 and the cylinder 1 away from each other, an outer productcontainer mantle 4, a compressed air flow-controlling valve assemblygenerally indicated by numeral 5, a spray nozzle 6 housed in the piston2, and a product metering device 7 and product flow control means,generally indicated by numeral 8, mounted on the outer end of the piston2, opposite the end thereof facing into the interior of the cylinder 1.

More in detail as seen in FIGS. 1 and 2, the valve assembly 5 has avalve housing part 10 constituted by a part, of reduced cross sectionaldiameter, of piston 2 extending into cylinder 1. A longitudinallyextending passage or duct 14 in piston 2 opens at one end into anenlarged recess 13, which in turn opens in the bottom of the valvehousing 10. The duct 14 opens at its other end into a chamber 38a beinga reduced diameter portion of a recess 38 in the sidewall of piston 2.

Aspirating spray nozzle 6 is formed as a Venturi nozzle insert 39 and ispositioned in the recess 38, leaving an annular product supply chamber37 around the nozzle insert. Radial product ducts 37a lead from thesupply chamber 37 to the Venturi neck portion 39a in nozzle insert 39,which connects the convergent chamber 39b, into which compressed air isintroduced via chamber 38a, with the divergent discharge chamber 390from which the product in aerosol form is sprayed out of the dispenser.The passage 14 forms a compressed air flow path through the valvehousing part 10 to the nozzle insert 39.

Against the bottom end portion 10a of the valve housing part 10 over therecess 13 therein, there is fastened an apertured, elastic valve seatdisk 34 held in place by the retaining ring 35 which is mounted by meansof a threading 35a on the reduced diameter end portion 10a of valvehousing part 10. Within the recess 13 and in engagement with the valveseat disk 34, there is provided a poppet valve member 15 which is urgedtoward the valve seat disk 34 by a return spring 23 positioned in therecess 13.

The cylinder 1 is fitted over valve housing part 10 of piston 2, andextends part of the way along the same. A transverse wall 11 in thecylinder 1 has an inwardly extending poppet valve-actuating pin 18thereon aligned with the central aperture in the valve seat disk 34.Piston return spring 3 is held between a supporting ring 12 about thepin 18 on the one hand and the retaining ring 35 of valve seat disk 34on the other hand.

The transverse wall 11 of cylinder 1 has apertures 33 therethroughopening into the interior of the compression chamber 17 therein. Anannular flexible gasket 36 which fits over pin 18, overlies theapertures 33, preferably closing each aperture by means of aperipherally loose flap portion 36a thereof, while its central portion36b is held in place about pin 18 on transverse wall 11 by means ofsupporting ring 12.

The assembly of gasket 36 and supporting ring 12 constitutes an airreturn means for admitting air into compression space 17 in cylinder 1,between transverse wall 11, and the front end of piston 2.

A first piston sealing ring 20 is positioned between the insidecylindrical surface of the cylinder 1 and the outer cylindrical surfaceof the valve housing part of piston 2, preferably by being inserted inan annular groove 35b of retaining ring 35. This O-ring prevents escapeof compressed air from, compression space 17. A hollow sleeve-shapedextension 9 extends downwardly from the transverse wall 11 of thecylinder 1 and has an open bottom end 9a.

A second piston sealing ring 21 is provided between a hollow collar part22 of cylinder 1, being of wider diameter than part 10, and the outsidewall of the upper part of piston 2. Sealing ring 21 ispreferably anO-ring placed about piston 2 in an annular groove 2a of the latter. Capscrew 19 screwed on to the top'end of cylinder 1 by means of threading19a prevents complete separation of cylinder 1 and piston 2 due to itscentral opening 19b being slightly narrower than the outer diameter ofsealing ring 21.

A product container 16. is formedby product.container mantle 4surrounding the-cylinder 1 andthe extension 9 thereof. The upper end of.the product container mantle 4 isthreaded at 4a, and is threadedlyjoined-to the collar part 22. of cylinder. 1, which surrounds the valvehousingpartlO ofipiston 2 and which has large vents or ports 22a.in itssidewall for the'passage of product fromthe product container 16. Ports22a extend downwardly in the wall of collar part 22 to where the latterpart joins the top end ofcylinder. 1' proper. Through these vents 220the interior 22b of "collar part 22 around valveh'ousing part 10 is incommunication with the interior of the product container 16.

The annular bottom wall 4b of the product container mantle 4 extendsover the open end 9a of cylinderextension 9 and is sealed thereto by aring gasket 25, and

an aperture 26 is provided in the bottom wall 4b of the container mantle4, opening into the hollow interior of the cylinder extension 9.

Extending axially through the piston 2 is a product channel 27 ofcrescent-shaped cross sectional area which has its inner end opening outof the upper sidewall of valve housing part 10 in to thesurroundinginterior 22b of collar part 22.

The sidewall of a metering cup 28 is inserted in a recess 28a which isprovided in the top end of piston 2, which projects to above the productcontainer 16 and beyond the nozzle insert 39. The metering cup 28 isclosed at thetop by a closure means, here shown as a cap 29 which isscrewed on to the top end of piston 2 by means of a threading 29a. Inthe sidewall of metering cup 28, windows 281; are provided through whichthe outer end of the product channel 27 is in communication via caprecess 30 with the interior of metering cup 28, the bottom 280 of therecess 28a is concave, and out of the bottom opens a product duct 31which extends through the top part of piston 2 into the pro duct-supplychamber 37. A product flow control means 8 is provided at the bottom ofmetering cup 28 in recess 28a, which control means 8 is here shown inthe form of a diaphragm 32, having a slit 32a therein.

The size and shape of the product container 16 is sufficiently large tohold a relatively large quantity of product, enough for the dispenser tobe operated a great number of times while dispensing only a small amountof product each time. The size of the metering cup 28, on the otherhand, is relatively small, containing only a small amount of product,which may be several times but is preferably slightly less than, thequantity which could be dispensed by the amount of compressed airavailable for each operation of the dispenser. The total volume of themetering cup 28, cap interior 29b and channel 27 is such that even themaximum amount of air flowing through the nozzle insert 29 cannotaspirate product from the product container 16 thereinto. In this way,the compressed air passing through the nozzle insert 39 aspiratesproduct only from the amount of product contained in the metering cup28.This'makes the device more efficient and accurate, since energyisnotused to draw product all the way to the nozzle insert from thecontainer 16. The metering chamber 28'is filled after every fewoperations or preferably after every operation, of the dispenser inamanner described hereinafter.

In operation the parts of the dispenser are normally in the positions asshown in FIG. 1. The spring 3 holds the cylinder 1 and the piston 2spaced apart, and the air passage through the air return means in thetransverse wallll of cylinder 1 is'free to open. It will be assumed thatthe metering cup28 isfilled withproduct. Pressure is the exerted on thebottom wall 4b of the product container l6 and'cylinder extension 9, andat the same time on'the cap 29, for example, by the thumb and forefingerof the hand, to urge the cylinder 1 and the piston 2' toward eachotherwhile compressing the spring 3; Theair compressed within the compressionchamber l7 of cylinder 1 presses the flaps 36a of air return gasket 36over apertures 33 and prevents flow of air therethrough. The poppetvalve member 15 is held seated by the spring-23 and the sealing ring 20prevents escape of compressed air from the compression chamber 17 pastthe gap between cylinder 1 and the valve housing portion 10 of piston 2.When the parts reach the positions'shown in FlG. 2, the actuating pin 18on the inside of the transverse wall 11 of the cylinder 1 engages thepoppet valve member 15 and lifts it from its seat 34. Compressed airthen escapes through the compressed air flow path formed by the recess13 and passage 14 and through the nozzle insert 39. The flow ofcompressed air through the nozzle insert creates a reduced pressurethrough the duct 31 and in the concave portion 280 ofthe recess 28a,thus causing the diaphragm 32 to bend downwardly'to open the slit 32a.Only the product in the metering cup 28 is aspirated through the duct31, and is entrained in the flow of compressed air and dispensed as avspray from the nozzle insert 39. No product is aspirated from theproduct container 16.

Release of the pressure on the parts of the dispenser enables the spring3 to urge the cylinder 1 and the piston 2 apart. The spring 23immediately seats the poppet valve member 15. The air return valve meansrelieves the vacuum within the compression chamber 17 of cylinder 1, andthe parts return to the positions of FIG. 1. This operation preferablyempties the metering cup 28. Then the device is inverted and productflows through product channel 27 into the metering cup 28 to refill it.The device is then ready for the next operation.

The arrangement of the collar part 22 around the valve housing part ofthe piston 2 and its connection to the cylinder 1 of which it forms anextension makes possible the admission of air to the product containerto break any vacuum which may be formed therein during aspiration ofproduct. As the cylinder 1 moves toward the piston 2 along the reduceddiameter valve housing part 10, the collar part 22 moves along theoutside of the valve housing part 10. When'the zone of the collar part22 containing the ports or vents 22a therein moves past the sealing ring21, the vents 22a will be open to the atmosphere through the spacebetween the collar part 22 and the outside of the piston 2. This willtake place each time the piston 2 is actuated to cause aspiration ofproduct. Ths aspiration will thus never have to take place against avacuum. This also enables the product to flow easily from the productcontainer 16 through the product flow path formed by the space 22baround the reduced diameter valve housing part 10 and the channel 27 tothe metering cup 28 when the dispenser is inverted. The diaphragm 32must be sufficiently rigid to prevent product from flowing through itsslit 32a when the dispenser is in the inverted position.

As the valve housing 10 forms part of the piston 2 within the cylinder1, this eliminates the need for a separately formed piston as has beenrequired in prior art dispensers. All parts of the dispenser thus arerelatively easily molded sleeves and body parts.

Moreover, by providing the metering cup 28 between the product container16 and the aspirating nozzle 39 the operation of the aspirating nozzle39 has been improved because it acts on only a relatively small body offluid. Nevertheless, the product container 16 can hold a sufficientamount of product to give the dispenser a long, useful life.

' In the embodiment of an aerosol dispenser according to the inventionshown in FIGS. 4 and 5, the metering device 7 is provided with a productoutlet control means which comprise, in lieu of the slit diaphragm 32,an accordion-type flexible, elastic unperforated mem-. brane 40 whichengages in its central fold the stem end 41a of a valve disk 41. Valvedisk 41 is seated, when in closed position, on a cylindrical upper wallportion 42 which can be integral with accordion-type membrane 40 and isheld in place in piston top recess 28a by means of the cylindrical wallof metering cup 28. Wall portion 42 has an orifice 42a therein throughwhich the interior of the metering space within the accordiontypemembrane40 below the valve disk 41 communicates with the annular productsupply chamber 37 of the spray nozzle 39 via a duct 43 in the topportion of the piston 2. Poppet valve member 15 of the compressed airflow-controlling valve means 5 has an elongated rod 44 on the sidethereof toward the metering device 7. This rod 44 extends into the duct14 and bears longitudinal grooves 44a so as to allow unim- 8 peded flowof compressed air through the latter duct toward nozzle insert 39.

The tip 44b of rod 44 may be in direct contact with the underside ofaccordion-type membrane 40 at all times, which would mean instantaneousopening of the product flow controlling means when actuating pin 18engages and raises poppet valve member 15. It is,.however, preferred tolocate the tip 44b of rod 44 a small distance beneath the underside ofaccordion-type membrane 40, whereby the product outlet control meansopen a short time, e.g., a fraction of a second, after the poppet valvemember 15 is raised from its seat disk 34, so that the product flowingthrough duct 43 will be entrained into the full stream of compressed airthrough Venturi neck portion 39a. If product were to flow through duct43 too early there would be the danger of having a larger productdroplet present in neck portion 39a which would lead to an initial sprayof higher product content than in the subsequently developed aerosolcloud.

It is a particular advantage of the dispenser according to the inventionthat there is no excess product flowing into the spray nozzle andremaining therein after spraying, which could lead to decomposition andclogging of the nozzle. If the volume of the metering cup 28 and that ofthe compression chamber 17 are so proportioned that there is stillcompressed air passing through Venturi neck portion 39a when productfrom the metering cup 28 has already been exhausted, the final stream ofcompressed air cleans the nozzle from residual product and guarantees alonger life of the nozzle.

As a further advantage of the embodiment shown in FIGS. 4 and 5, thevalve housing part 10 is detachably connected by means of a threading10b to the upper portion 2b of piston 2. It is thus easy to remove thevalve housing part 10 as well as the cap 29 and metering device 7 frompiston upper portion 2b and replace the latter including the spraynozzle housed therein by a new piston and nozzle insert, whilepreserving the more expensive parts containing valves, springs, etc.

I claim:

1. An aerosol dispenser for fluid products, comprising container meansfor product to be dispensed,

a piston pump separately from the product container and having a pistonand a cylinder and an air compression space therein,

a spray nozzle in which compressed air flowing therethrough aspirates,and from which it sprays, product in aerosol form,

duct means for compressed air flow, extending as a flowpath from saidpiston pump to said spray nozzle,

compressed air flow-controlling valve means in said flowpath andcomprising a valve member movable in a valve housing and obturating thecompressed air flowpath when closed,

a product flowpath separate from said compressed air flowpath,

product flow control means in said product flowpath,

engaging means provided between said compressed air flow-controllingvalve means and said cylinder, which engaging means comprises anabutting part on the inside of the end wall of the compression space insaid cylinder and a projection of said valve member extending out of thefront face of said piston facing toward said compression space end wallwhen out of contact with said abutting part, and

a product metering device mounted on the said piston adjacent said spraynozzle in said product flowpath;

said product flow control means comprising a valve member biassed towardclosed position and being provided with abutting means in an open end ofsaid compressed air flow duct in said piston, said valve membercomprising contact rod means extending through said airflow duct andengaging said abutting means of said product flow control means andthereby opening the product flowpath, when said abutment means in thepiston pump act on the valve body of said compressed airflow-controlling valve means;

wherein at least the front end part of said piston extending into saidcylinder constitutes the said valve housing of the compressed airflow-controlling valve means, said spray nozzle is fixedly mounted insaid piston, and said duct means for compressed air flow extends throughthe piston,

said product flow control means are located between said metering deviceand said spray nozzle, said product container means comprises a productreservoir surrounding the cylinder of said piston pump and the saidproduct flowpath extends from said reservoir to said metering devicethrough a part of said piston sealingly separated from the aircompression space in said cylinder.

2. An aerosol dispenser as described in claim 1, in which said meteringchamber is disposed on one side of said spray nozzle in the direction ofthe relative movement of said cylinder about said piston, and saidproduct reservoir is disposed on the opposite side of said spray nozzle,whereby product can be caused to flow from the product container to themetering chamber by inverting the dispenser.

3. An aerosol dispenser as described in claim 1 in which said productreservoir is provided around said valve housing part of said piston andis connected to said cylinder for movement therewith, said productreservoir bring in free communication with part of the interior of saidcylinder separated sealing by from the compression space of the latter,and being in sliding and sealing engagement with said piston.

4. An aerosol dispenser as described in claim 3 in which air returnmeans is provided between said product reservoir and said valve housingpart of said piston for admitting air to said product reservoir at theend of each compression stroke of said piston.

5. An aerosol dispenser as described in claim 4 in which said productreservoir has a collar part at the top thereof around said valve housingpart of said piston and, a sealing ring in sliding sealing engagement between said collar part and said valve housing part, said productflowpath through said piston opening out of said valve housing partwithin said cylinder interior part in communication with said reservoir.

6. An aerosol dispenser as described in claim 5 in which said collarpart has a hollow interior about said valve housing part of said piston,and at least one vent is provided in the wall of said collar partthrough which vent said product flow path opens into said reservoir,said collar part moving relative to said sealing ring on said valvehousing part during a compression stroke, whereby said vent extends pastsaid sealing ring at the end of said compression stroke to place theinterior of said reservoir in communication with the outside atmosphere.

7. An aerosol dispenser as described in claim 1, wherein said compressedair flow-controlling valve means comprise spring means and a valve seatin said valve housing, said spring means urging said valve memberagainst said valve seat.

8. An aerosol dispenser as described in claim 1, wherein one way valvemeans for admitting air into said cylinder compression space during thereturn stroke of said piston are mounted in the wall of said cylinder.

9. An aerosol dispenser as described in claim 1, wherein said productflow control means comprise valve seat means engaged by said productvalve member when in closed position and elastically deformable membranemeans engaging said product valve member and biassing the latter intoengagement with said valve seat means.

1. An aerosol dispenser for fluid products, comprising container meansfor product to be dispensed, a piston pump separately from the productcontainer and having a piston and a cylinder and an air compressionspace therein, a spray nozzle in which compressed air flowingtherethrough aspirates, and from which it sprays, product in aerosolform, duct means for compressed air flow, extending as a flowpath fromsaid piston pump to said spray nozzle, compressed air flow-controllingvaLve means in said flowpath and comprising a valve member movable in avalve housing and obturating the compressed air flowpath when closed, aproduct flowpath separate from said compressed air flowpath, productflow control means in said product flowpath, engaging means providedbetween said compressed air flowcontrolling valve means and saidcylinder, which engaging means comprises an abutting part on the insideof the end wall of the compression space in said cylinder and aprojection of said valve member extending out of the front face of saidpiston facing toward said compression space end wall when out of contactwith said abutting part, and a product metering device mounted on thesaid piston adjacent said spray nozzle in said product flowpath; saidproduct flow control means comprising a valve member biassed towardclosed position and being provided with abutting means in an open end ofsaid compressed air flow duct in said piston, said valve membercomprising contact rod means extending through said air flow duct andengaging said abutting means of said product flow control means andthereby opening the product flowpath, when said abutment means in thepiston pump act on the valve body of said compressed airflow-controlling valve means; wherein at least the front end part ofsaid piston extending into said cylinder constitutes the said valvehousing of the compressed air flow-controlling valve means, said spraynozzle is fixedly mounted in said piston, and said duct means forcompressed air flow extends through the piston, said product flowcontrol means are located between said metering device and said spraynozzle, said product container means comprises a product reservoirsurrounding the cylinder of said piston pump and the said productflowpath extends from said reservoir to said metering device through apart of said piston sealingly separated from the air compression spacein said cylinder.
 2. An aerosol dispenser as described in claim 1, inwhich said metering chamber is disposed on one side of said spray nozzlein the direction of the relative movement of said cylinder about saidpiston, and said product reservoir is disposed on the opposite side ofsaid spray nozzle, whereby product can be caused to flow from theproduct container to the metering chamber by inverting the dispenser. 3.An aerosol dispenser as described in claim 1 in which said productreservoir is provided around said valve housing part of said piston andis connected to said cylinder for movement therewith, said productreservoir bring in free communication with part of the interior of saidcylinder separated sealing by from the compression space of the latter,and being in sliding and sealing engagement with said piston.
 4. Anaerosol dispenser as described in claim 3 in which air return means isprovided between said product reservoir and said valve housing part ofsaid piston for admitting air to said product reservoir at the end ofeach compression stroke of said piston.
 5. An aerosol dispenser asdescribed in claim 4 in which said product reservoir has a collar partat the top thereof around said valve housing part of said piston and, asealing ring in sliding sealing engagement between said collar part andsaid valve housing part, said product flowpath through said pistonopening out of said valve housing part within said cylinder interiorpart in communication with said reservoir.
 6. An aerosol dispenser asdescribed in claim 5 in which said collar part has a hollow interiorabout said valve housing part of said piston, and at least one vent isprovided in the wall of said collar part through which vent said productflow path opens into said reservoir, said collar part moving relative tosaid sealing ring on said valve housing part during a compressionstroke, whereby said vent extends past said sealing ring at the end ofsaid compression stroke to place the interior of said reservoir incommunication with the outside atmosphere.
 7. An aerosol dispenser asdescribed in claim 1, wherein said compressed air flow-controlling valvemeans comprise spring means and a valve seat in said valve housing, saidspring means urging said valve member against said valve seat.
 8. Anaerosol dispenser as described in claim 1, wherein one way valve meansfor admitting air into said cylinder compression space during the returnstroke of said piston are mounted in the wall of said cylinder.
 9. Anaerosol dispenser as described in claim 1, wherein said product flowcontrol means comprise valve seat means engaged by said product valvemember when in closed position and elastically deformable membrane meansengaging said product valve member and biassing the latter intoengagement with said valve seat means.